Air Filter



FIG. 1 is a perspective view of the air filter showing my new design;

FIG. 2 is a top view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a right side view thereof, the left side being a mirror image of the right side shown;

FIG. 5 is a rear view thereof;

FIG. 6 is a bottom view thereof. _ 

The ornamental design for an air filter, substantially as shown and described. 